The involvement of growth hormone in regulating liver glutamine synthetase and the interrelationship of this regulation with the hormone's enhancement of hepatic glucose production, will be investigated. We intend to examine: 1) The effects of hypophysectomy and growth hormone treatment on the rates of degradation and synthesis of the enzyme. 2) Whether glutamine synthetase activity is lower in dwarf mice. 3) Whether hormone responsive and unresponsive forms of the enzyme exist in liver. 4) Whether the somatomedins are mediators for growth hormone action on glutamine synthetase.